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1 // Copyright (c) 2012 The Chromium Authors. All rights reserved. | 1 // Copyright (c) 2012 The Chromium Authors. All rights reserved. |
2 // Use of this source code is governed by a BSD-style license that can be | 2 // Use of this source code is governed by a BSD-style license that can be |
3 // found in the LICENSE file. | 3 // found in the LICENSE file. |
4 | 4 |
5 #include "base/memory/shared_memory.h" | 5 #include "base/memory/shared_memory.h" |
6 | 6 |
7 #include <errno.h> | 7 #include <errno.h> |
8 #include <fcntl.h> | 8 #include <fcntl.h> |
9 #include <stddef.h> | 9 #include <stddef.h> |
10 #include <sys/mman.h> | 10 #include <sys/mman.h> |
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362 *path = temp_dir.AppendASCII(name_base + ".shmem." + mem_name); | 362 *path = temp_dir.AppendASCII(name_base + ".shmem." + mem_name); |
363 return true; | 363 return true; |
364 } | 364 } |
365 #endif // !defined(OS_ANDROID) | 365 #endif // !defined(OS_ANDROID) |
366 | 366 |
367 SharedMemoryHandle SharedMemory::GetReadOnlyHandle() { | 367 SharedMemoryHandle SharedMemory::GetReadOnlyHandle() { |
368 CHECK(readonly_shm_.IsValid()); | 368 CHECK(readonly_shm_.IsValid()); |
369 return readonly_shm_.Duplicate(); | 369 return readonly_shm_.Duplicate(); |
370 } | 370 } |
371 | 371 |
372 bool SharedMemory::GetUniqueId(SharedMemory::UniqueId* id) const { | |
373 // This function is called just after mmap. fstat is a system call that might | |
374 // cause I/O. It's safe to call fstat here because mmap for shared memory is | |
375 // called in two cases: | |
376 // 1) To handle file-mapped memory | |
377 // 2) To handle annonymous shared memory | |
378 // In 1), I/O is already permitted. In 2), the backend is on page cache and | |
379 // fstat doesn't cause I/O access to the disk. See the discussion at | |
380 // crbug.com/604726#c41. | |
381 base::ThreadRestrictions::ScopedAllowIO allow_io; | |
382 struct stat file_stat; | |
383 if (HANDLE_EINTR( | |
384 ::fstat(static_cast<int>(handle().GetHandle()), &file_stat)) != 0) | |
385 return false; | |
386 id->first = file_stat.st_dev; | |
387 id->second = file_stat.st_ino; | |
388 return true; | |
389 } | |
390 | |
391 } // namespace base | 372 } // namespace base |
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